Looks like a pretty well-researched, balance report ...
Amid Skepticism, HIV Clinics Put Urine Screening to the Test
7.09 a.m. ET (1109 GMT) June 9, 1998
By Marian Jones, Fox News
Dixie Cups could soon replace syringes as the chief tool of HIV testing with the FDA approval of a new urine test to detect the human immunodeficiency virus. But this method, the first available alternative to blood testing, comes onto the market embroiled in controversy over its accuracy.
Some doctors believe urine testing will become the preferred HIV screening method around the world. "It is much more acceptable to the individual to have a urine sample than to have a needle stick and have blood drawn," says Ronald Gray, M.D., M.Sc., an epidemiologist at Johns Hopkins University.
"Urine is also much safer for health care personnel," he added. "You don't have the risk of needle sticks or of handling potentially dangerous material in the labs."
When issuing its final approval last Monday, however, the FDA warned that the urine test is not as accurate as blood tests and that it causes more false-positive results, leading some AIDS health care providers to doubt whether the urine test will ever replace blood tests in U.S. clinics.
"If you have something that meets such a high standard of accuracy [as the blood test], why use anything less?", asks Beth Gery, M.D., director of the David Geffen Center for HIV education in New York, a major AIDS testing center.
The test's manufacturer, Calypte Biomedical of Berkeley, Calif., has disputed the FDA's warnings. "The blood test is an extremely good test, but it's not perfect," says Bill Boeger, Calypte's CEO. "I would say the same of the urine test."
In one study, the urine test missed two infected people out of 748 who had tested HIV-positive with blood tests. The two who were missed had AIDS and were undergoing antiretroviral therapy, which lowers the amount of virus in the blood to undetectable levels and can lower the amount of antibodies as well, Calypte asserts.
If the antiretroviral therapy was indeed the cause of these inaccurate results, then it should not be considered flawed, Gray argues, as people on antiretroviral medications already know they have HIV.
In another study, three people out of 391 high-risk individuals tested positive for HIV with the urine test but not the blood test. The FDA has labeled these as false positives, but Calypte argues that they should instead be considered "discordant" results, and that people in question may have actually had HIV antibodies in their urine but not their blood.
"It is theoretically possible that an individual could have a localized HIV infection with antibody-producing cells that are not detected in the blood," says Ann A. Kiessling, M.D., an immunology researcher at Harvard Medical School. This is especially true given that the urine test detects a different kind of antibody than the blood test does, Kiessling says.
Calypte is planning follow-up studies to determine whether the urine tests really detect HIV antibodies that blood tests fail to pick up, or whether the "discordant" results are in fact false positives, according to Howard Urnovitz, M.D., the company's founder and chief scientist.
In the meantime, some doctors do see urine testing as a low-hassle way for doctors to screen low-to-medium-risk populations. "It could be used in physicians' offices and other areas where people want to do routine screening for HIV," speculates Richard Marlink, M.D., Director of the Harvard AIDS Institute.
Leading AIDS activists, however, see few new advantages. Like the blood test, the urine test requires the person being tested to return at a later time for results.
"You see a big drop-off in the number of people who actually return for test results," says Spencer Cox of Treatment Action Group, a nonprofit AIDS research and treatment advocacy organization. "Any new reasonably accurate diagnostic test is useful. But what's really needed are tests that can be rapidly administered."
An oral HIV test, in which a pad is used to take a sample of fluid from blood vessels in the cheek, has been on the market since 1996. This test, like the urine test, was hailed by the media as a needle-free advance over blood tests.
The test's manufacturer, OraSure, claims that it is over 99 percent accurate, but AIDS health care administrators still use a blood test for confirmation of positive test results on an oral test, Gery says.
Whether or not the urine test becomes popular in the United States, experts agree it offers logistical advantages for HIV detection in the developing world.
According to a December 1997 World Health Organization report, nine out of 10 HIV-infected people in the world do not know that they have the virus.
This lack of knowledge is especially critical for pregnant women, says Marlink, because previous studies have shown that administration of the drug AZT during pregnancy sharply reduces the baby's chance of being born HIV-positive.
Blood testing is prohibitively expensive in many countries because of the training and equipment it requires. A health care worker must be instructed on how to draw blood, spin the sample to separate the cells from the serum, freeze the serum and send it to a lab. The process requires a centrifuge and sterilized needles.
Urine testing only involves training a person to collect a cup, label it and store it in a refrigerator where it can remain for up to 56 days, notes Gray, who has used the tests on research populations in Africa. "The field workers in our study have no previous health care training. They simply collect samples near a person's home, which is so much easier than blood tests."
This does not mean the urine test will necessarily be cheaper, cautions Marlink. "If people are locked into a package testing kit produced in the West, and don't have the training, infrastructure and capability to alter the test to fit their needs, then the pricing could be too high to fit the needs of developing countries."
Additionally, in Western Africa, where a second strain of the virus, HIV-2, is prevalent, this test will have limited application, as it only tests for HIV-1.
However, an HIV-2 urine test may be available someday, say experts, especially if urine testing becomes feasible in Africa. But for now, it remains to be seen whether a Dixie Cup revolution of urine HIV testing will occur any time soon. |
